[ Providers ] Make API-Key optional and improve errors

[rlajous]

Description

Please provide a short description of the changes in this pull request.

Fixes # (issue)

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation update (if none of the other choices apply)

Checklist

• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [ ] I have updated the documentation accordingly.

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